Melanoma, the most serious form of skin cancer, accounts for more than 75% of all skin cancer deaths. Despite repeated health warnings based on proven science that overexposure to ultraviolet (UV) light is the most preventable cause of all skin cancers, including melanoma, many Americans are not properly protecting themselves from this known carcinogen. Now, new understanding of the emerging field of genetic epidemiology of melanoma and the factors that influence teens' use of indoor tanning could shed more light on ways to protect future generations from skin cancer.

At the American Academy of Dermatology's Summer Academy Meeting 2008 in Chicago, dermatologist Martin A. Weinstock, MD, PhD, professor of dermatology and community health at Brown University in Providence, RI, and chief dermatologist at the Veterans Affairs Medical Center in Providence, led the presentation of key findings from research that could pave the way for future skin cancer prevention and treatment strategies.

Link between UV exposure and melanoma: The gene factor

When it comes to melanoma, there are multiple types of melanoma that can occur throughout the body and their relationship to UV exposure is different from one type of melanoma to another.

Weinstock explained that over the past few years, the fields of genomics and genetic epidemiology have been advancing tremendously. The role of genetics in the study of melanoma is an attempt to understand the connection between genetic changes in melanoma associated with different types of melanoma.

"Everyone is born with genes that are inherited from their parents," said Weinstock. "Sometimes the genes in certain skin cells become mutated, deleted or amplified over time due to UV radiation and other factors, and these genetic changes in skin cells that take place could result in melanoma."

Different types of melanoma also are characterized by different genetic changes. For example, Weinstock explained a melanoma that occurs on the face of an older person with extensive sun exposure will have a different genetic make-up than a melanoma found on the back or trunk area of a younger person with more limited exposure to UV light. From this greater understanding of the genetic characteristics of different types of melanomas, Weinstock suggested further research could show which preventative behaviors at different ages could help decrease the incidence of age-related melanomas.

A greater understanding of the relationship between UV exposure and melanoma could lead to more implications for treatment and preventive measures. For example, Weinstock noted that the oncology community is hopeful that a specific chemotherapy could be developed in the future that would target each type of melanoma based on where they occur on the body and their genetic characteristics.

"The better we understand the different types of melanoma, the more we can direct our therapies and prevention efforts," said Weinstock. "Since these new therapies won't be available anytime soon, it's still important for people to protect their skin from UV radiation from the sun and tanning beds."

Influences on teens' use of indoor tanning

Despite its link to both melanoma and squamous cell carcinoma, indoor tanning is big business. In fact, published reports indicate that the indoor tanning industry has an estimated revenue of $5 billion, a fivefold increase from 1992. The prevalence of indoor tanning among older U.S. teen girls is as high as 40%.

A multi-component project to identify the factors that influence the likelihood of indoor tanning, known as CITY 100 (Correlates of Indoor Tanning in Youth), examined the environmental, policy and individual level variables that may be related to teens' use of indoor tanning in 100 of the most populous U.S. cities. The primary component used to gather data consisted of a phone survey of 6,125 teen/parent pairs, with the teen sample ranging in age from 14 to 17. It was noted that 52% of the teen sample was female, 69% was classified as non-Hispanic white, and approximately 10.4% had used indoor tanning in the past year.

Other facets of the study included analyzing the presence and stringency of state indoor tanning legislation; evaluating local enforcement of state laws; assessing the density (per population) of tanning facilities in each city (i.e., availability); and assessing the practices of tanning facilities related to youth access, including parental consent, banning teens based on age, and the frequency teens were allowed to tan their first week.

The study found that only 28 states had any type of indoor tanning law, with 21 of these states having a youth access law. Even the majority of states with tanning laws that were reviewed did not perform annual inspections, and 70% of the facilities said they would allow a fair-skinned, 15-year-old girl who had never used an indoor tanning facility to tan every day the first week of tanning.

"Access to indoor tanning was found to be a significant contributing factor in teens use of these facilities," said Weinstock. "The study found that having a higher density of facilities in one's city and having at least one facility within two miles of one's home were each significantly related to indoor tanning. In fact, the lead investigator pointed out that the mean number of tanning facilities per city exceeded the number of Starbucks locations, and 89% of the teens in the sample lived within three miles of a tanning facility."

Weinstock also noted the individual influences that were significantly associated with a higher likelihood of tanning included being female, older, or non-Hispanic white; having parents or friends who tan indoors; believing that tans are attractive; being exposed to ads; and having higher household incomes or weekly allowances.

"Teens appear to be a primary target of the indoor tanning industry, which resembles the tobacco industry in distorting science with the likely result of confusing the public about the facts," said Weinstock. "We hope these findings will demonstrate the need for tighter regulations and enforcement of this unhealthy practice."

In the interest of protecting public health, the American Academy of Dermatology Association (AADA) opposes indoor tanning and supports a ban on the production and sale of indoor tanning equipment for non-medical purposes. In the meantime, the AADA advocates for youth access laws until the Food and Drug Administration (FDA) takes action.

For more information about skin cancer, please visit the SkinCancerNet section on www.skincarephysicians.com, a Web site developed by dermatologists that provides patients with up-to-date information on the treatment and management of disorders of the skin, hair and nails.

Headquartered in Schaumburg, IL, the American Academy of Dermatology, founded in 1938, is one of the largest, most influential, and most representative of all dermatologic associations. With a membership of more than 15,000 physicians worldwide, the Academy is committed to: advancing the diagnosis and medical, surgical and cosmetic treatment of the skin, hair and nails; advocating high standards in clinical practice, education, and research in dermatology; and supporting and enhancing patient care for a lifetime of healthier skin, hair and nails. For more information, visit the Academy's Web site at www.aad.org.